A pneumatic tire has been required to reduce a noise and improve quietness when a vehicle is running. As such, there is a technique to reduce an external noise of the vehicle by using a resonator (i.e., what is called a Helmholtz resonator) constituted by using a gas chamber and a branch groove.
For example, PLT 1 set forth below suggests a technique having one circumferential main groove formed on a tread surface and a circumferential sub-groove intermittently extending in a tread circumferential direction within a land portion adjacent to the circumferential main groove, wherein the circumferential sub-groove opens to the circumferential main groove via one inclined groove.